The study was funded by an internal grant from the Meijer Heart and Vascular Institute at Spectrum Health.

The protocol was approved by the Michigan State University Institutional Animal Care and Use Committee (IACUC) (Protocol 2020-035, approved on 7/27/2020). For this study, 20 adult male sheep weighing 62 &#177; 7 kg were used.
1. Preoperative steps
<ol>
	<li>Fast the animal 12 h prior to surgery (overnight).</li>
	<li>Place the animal in a sheep chair (Figure 1), and prepare for the right jugular vein cannulation using a long 11 Fr introducer sheath (sheath length = 10 cm).</li>
	<li>Shave with clippers along the IV placement site-the right anterior aspect of the neck around 10-15 cm lateral from the midline for the right jugular vein.</li>
	<li>Turn the animal&#39;s head to the left so that the right anterior and lateral aspects of the neck are exposed. Localize the jugular vein course. To facilitate this, compress the bottom of the neck to distend the vein.</li>
	<li>Clean with chlorhexidine and alcohol-based scrub, and anesthetize locally with 1% lidocaine.</li>
	<li>Canulate the jugular vein in the mid to upper third of the neck, as described.
	<ol>
		<li>Cut the skin above the vein with a number 11 blade perpendicular to the vein.</li>
		<li>Cannulate with a 14 G angiocatheter; when in place (blood is coming out of the needle or blood is spotted), remove the needle, leave the catheter, pass the guidewire, remove the catheter, place the 11 Fr sheath, and secure it.</li>
		<li>Ensure the patency and proper placement of the cannula by withdrawing dark-red blood and performing a saline flush to confirm the flow and absence of swelling at the insertion site.</li>
	</ol>
	</li>
	<li>Start the induction of propofol at 1.0-1.5 mg/kg intravenous (IV).</li>
	<li>Intubate with a number 9 endotracheal (ET) tube using a laryngoscope with a number 5 blade. For this, one person should secure&#160;the jaws and tongue, while the other person identifies&#160;the trachea, inserts the ET tube, and inflates the sealing cuff. Confirm proper placement by the bilateral breath sounds and condensation on the ET tube.</li>
	<li>Administer intravenously the analgesic buprenorphine at 0.01 mg/kg and use 240 mg of gentamicin and 1 g of cefazolin&#160;for antibiotic prophylaxis.</li>
	<li>Transfer the animal from the sheep chair onto a surgical table, and position it on its right side.</li>
</ol>
2. Surgery steps
<ol>
	<li>Ventilate at 15 mL/kg (12-18 breaths/min), with oxygen flow at 4 L/min and isoflurane at 2.5%-4.0%. Confirm proper anesthesia to ensure the subject is at the surgical level (stage 3) by checking the jaw tone and eye rotation.</li>
	<li>Lubricate both eyes by applying ophthalmic oinment&#160;and insert a gastric tube to ensure gas and food evacuation. Connect the electrocardiogram (EKG), pulse oximeter (SpO2), capnograph (ETCO2), and body temperature monitors. Attach the EKG limb leads (I, II, III) to the skin via alligator clips, the SpO2 sensor to the animal&#39;s cheek, and the ETCO2 tube to the endotracheal tube, and pass the temperature probe through the nostril into the nasopharynx.</li>
	<li>Prepare the operative field. Shave the left anterior thorax, clean with chlorhexidine and alcohol-based scrub, and cover with sterile drapes.</li>
	<li>Make a 10 cm long skin and subcutaneous incision at the level of the fourth intercostal space.</li>
	<li>Confirm the correct intercostal space by identifying the thoracic inlet and counting the intercostal spaces downward. Subsequently, continue the incision in the center and along the fourth intercostal space.</li>
	<li>Divide the intercostal muscles, open the chest cavity, and spread the ribs with a mini-thoracotomy Finochietto-style retractor. While performing the thoracotomy, take care not to injure the left internal mammary artery (LIMA) at the sternal border of the incision and the lung at the superior border.</li>
	<li>Perform baseline epicardial echocardiography to assess the biventricular function and valvular competence. The occurrence of non-standard views may be due to the mini-thoracotomy focused on the tricuspid valve (TV), right and left ventricular function, and pulmonary artery flow.</li>
	<li>Identify the LIMA at the sternal border of the incision, remove the adjacent tissues around it, and prepare to establish an arterial line for pressure monitoring.</li>
	<li>Place two 4-0 silk sutures around the artery, with one proximal and one distal to the cannulation site (used to secure the arterial catheter).</li>
	<li>Use titanium clips with a clip applier to clip the LIMA distal to the planned cannulation site to prevent backflow bleeding during cannulation.</li>
	<li>Make a perpendicular incision that is half of the circumference of the catheter in the LIMA with a number 11 blade.</li>
	<li>Insert an 18 G angiocatheter, and attach it to the arterial line module. When a pressure of around 120/80mmHg is reached, secure the catheter in place using the two 4-0 silk sutures placed earlier.</li>
	<li>Perform pericardiotomy starting at the level of pulmonary artery sinuses and going 4-5 cm laterally along the main pulmonary artery (MPA), taking care not to injure the left phrenic nerve.</li>
	<li>Apply four to five retraction stitches to the opened pericardium to create a pericardial well, as this facilitates exposure and dissection between the pulmonary trunk and aorta.</li>
	<li>Dissect the MPA from ascending aorta (AA) around 2-3 cm from its origin using blunt right-angle forceps,&#160;starting at the level of the left atrial appendage and working toward the AA. To fully separate the MPA from the AA, use electrocautery or scissors to remove the connective tissue between the two structures.</li>
	<li>Pass an umbilical tape around the MPA with a blunt right-angle clamp. Establish an MPA pressure line by placing a 5-0 monofilament purse-string suture 1 cm distal from the MPA sinuses.</li>
	<li>Insert a 20 G angiocatheter, and connect it to a monitoring line. Ensure correct MPA and arterial line readings are achieved prior to cinching the umbilical tape; the arterial and pulmonary pressures may vary but should be comparable to human patient values.</li>
	<li>Hold both ends of the umbilical tape, and clip them together to reduce the lumen of the MPA.</li>
	<li>Progressively tighten the band with the successive application of a clip applier, with each clip placed below the previous clip until the systemic blood pressure begins to steadily decline (Figure 2). At this point, remove the last placed clip to stabilize the systemic blood pressure.</li>
	<li>When maximal cinching and stable hemodynamic conditions are achieved, secure the umbilical tape to the adventitia of the MPA using a 5-0 monofilament suture to avoid distal migration.</li>
	<li>Perform post-banding echocardiography to assess the biventricular function and valvular competence, as in step 2.7. Remove the MPA pressure line and arterial line, and ensure good hemostasis by checking for any bleeding coming from the area where the band and arterial lines were placed.</li>
	<li>Place a chest tube into the left thorax, with the entry site one intercostal space below the initial incision. Close the ribs with two Vicryl size 2&#160;sutures, and close the wound with three-layer continuous sutures: Vicryl 2-0 for the muscle and subcutaneous tissues and Prolene 3-0 for the skin.</li>
	<li>When no signs of bleeding are seen, remove the chest tube before weaning the animal from the ventilator.</li>
	<li>Wean the animal from the ventilator, extubate, move it to a single cage, and closely follow it for at least 1 h. Leave the central IV line in place, and secure it using a loosely applied bandage around the neck. 
	NOTE:&#160;Postoperative intravenous analgesia was maintained with buprenorphine (0,05 mg/kg) and Flunixin (1.2 mg/kg) for 3&#160;days post-surgery.&#160;</li>
</ol>

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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Right+ventricular+function+in+cardiovascular+disease,+part+I:+Anatomy,+physiology,+aging,+and+functional+Assessment+of+the+right+ventricle.">Right ventricular function in cardiovascular disease, part I: Anatomy, physiology, aging, and functional Assessment of the right ventricle.</a> Circulation. 117 (11), 1436-1448 (2008).</li><li>Taramasso, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+growing+clinical+importance+of+secondary+tricuspid+regurgitation.">The growing clinical importance of secondary tricuspid regurgitation.</a> Journal of the American College of Cardiology. 59 (8), 703-710 (2012).</li><li>Mangieri, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanism+and+implications+of+the+tricuspid+regurgitation:+From+the+pathophysiology+to+the+current+and+future+therapeutic+options.">Mechanism and implications of the tricuspid regurgitation: From the pathophysiology to the current and future therapeutic options.</a> Circulation: Cardiovascular Interventions. 10 (7), 005043 (2017).</li><li>Otto, C. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2020+ACC/AHA+Guideline+for+the+Management+of+Patients+With+Valvular+Heart+Disease:+Executive+summary:+A+report+of+the+American+College+of+Cardiology/American+Heart+Association+Joint+Committee+on+Clinical+Practice+Guidelines.">2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: Executive summary: A report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines.</a> Circulation. 143 (5), 35-71 (2021).</li><li>Vonk-Noordegraaf, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Right+heart+adaptation+to+pulmonary+arterial+hypertension:+physiology+and+pathobiology.">Right heart adaptation to pulmonary arterial hypertension: physiology and pathobiology.</a> Journal of the American College of Cardiology. 62, 22-33 (2013).</li><li>Yoganathan, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tricuspid+valve+diseases:+Interventions+on+the+forgotten+heart+valve.">Tricuspid valve diseases: Interventions on the forgotten heart valve.</a> Journal of Cardiac Surgery. 36 (1), 219-228 (2021).</li><li>Vachi&#233;ry, J. 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The authors have no conflicts of interest to disclose.

In this model, 8 weeks of pulmonary artery banding resulted in a stable chronic ovine model of right ventricular dysfunction and, in most cases, significant FTR. The strengths of the presented chronic PAB model include the precise afterload adjustment during the procedure, although its influence on RV responses may differ. The model is suitable for evaluating varying degrees of RV failure or FTR, with the severity modulated by the degree of pulmonary artery constriction. Moreover, the application of fixed and stable resi...

Right ventricular failure (RVF) is recognized as an important factor contributing to the morbidity and mortality of cardiac patients. The most common causes of RVF are left-sided heart disease and pulmonary hypertension1. During the progression of RVF, functional tricuspid regurgitation (FTR) may arise as a consequence of right ventricular (RV) dysfunction, annular dilatation, and subvalvular remodeling. Moderate to severe FTR is an independent predictor of mortality2,3, and it is estimated that 80%-90% of tricuspid regurgitation cases are functional in nature4. FTR itself may promote adverse ventricular remodeling by influencing either afterload or preload5. The tricuspid valve has historically been considered the forgotten valve6, and it was believed that the treatment of left-sided heart disease would resolve the associated RV pathology and FTR7. Recent data have shown this to be a faulty strategy, and current clinical guidelines advocate a much more aggressive approach to FTR4. However, the pathophysiology of severe FTR associated with right ventricular dysfunction is still poorly understood, leading to suboptimal clinical results8. The currently available large animal models of RVF are based on pressure, volume, or mixed overload. We have previously described a large animal model of RVF and TR but only in an acute setting9.
The current study focuses on a chronic ovine model of pulmonary artery banding (PAB) to increase RV afterload (pressure overload) and induce RV dysfunction and FTR. The afterload model is reliable and reproducible compared to pulmonary hypertension models, in which changes in microvasculature are less predictable and more likely10. The goal of the study was to develop a chronic large animal model of RVF and FTR that would most accurately mimic RV pressure overload in patients with left-sided heart disease and pulmonary hypertension. The establishment of such a model would permit in-depth studies on the pathophysiology of the ventricular and valvular remodeling associated with RV dysfunction and tricuspid insufficiency. The ovine model was chosen based on our prior work on the mitral valve and the published literature supporting the anatomical and physiological similarities between human and ovine hearts11,12,13.
For this study, 20 adult sheep (62 &#177; 7 kg) underwent a left thoracotomy and main pulmonary artery banding (PAB) to at least double the systolic pulmonary artery pressure (SPAP), thus inducing RV pressure overload. The animals were followed for 8 weeks, and the symptoms of heart failure were treated with diuretics when clinically apparent. Surveillance echocardiography was performed periodically to assess RV function and valvular competence. Following the completion of the experimental protocol for model development (8 weeks), the animals were taken back to the operating room for median sternotomy and the implantation of sonomicrometry crystals on the epicardial and intra-cardiac structures. This procedure was performed using cardiopulmonary bypass with the heart beating and with bicaval control. There were no problems in weaning the animals from the cardiopulmonary bypass or acquiring the sonomicrometry data in a stable steady-state hemodynamic environment without the need for inotropes for right heart support. We anticipate performing tricuspid ring annuloplasty and other right heart procedures in the near future using a right thoracotomy approach in both terminal and survival experiments. The current experience leads us to believe that it will be possible to wean the animals from the cardiopulmonary bypass without difficulty and that long-term survival is feasible. As such, we believe the model will permit the performance of clinically pertinent cardiac procedures. Below is a description of the steps (perioperative and operative) performed for carrying out the ovine experimental protocol.

<table><tbody><tr><td>Anesthesia Machine Drager Narkomed MRI-2</td><td>Drager</td><td>4116091-001</td><td></td></tr><tr><td>angiocatheter</td><td>BD</td><td>BD382268</td><td>14GAx8.25cm</td></tr><tr><td>BD ChloraPrep Scrub Teal 26 ml applicator with a sterile solution</td><td></td><td></td><td></td></tr><tr><td>Blade #11</td><td>Bard-Parker</td><td>371111</td><td></td></tr><tr><td>Buprenorphine&amp;nbsp;</td><td>HIKMA</td><td></td><td></td></tr><tr><td>cefazolin 1.0g</td><td>Hikma</td><td>0143-9924-90</td><td></td></tr><tr><td>Diprivan 200mg/20ml</td><td>63323-0269-29</td><td>FRESENIUS KABI</td><td></td></tr><tr><td>Electrosurgical generator Valleylab Force FX</td><td>Valleylab</td><td>CF5L44233A</td><td></td></tr><tr><td>Gentamicin Sulfate 40 mg / mL</td><td>Fresenius</td><td>406365</td><td></td></tr><tr><td>i-Stat Blood analyzer MN 300</td><td>Abbott</td><td></td><td></td></tr><tr><td>Lidocaine HCl 1%</td><td>Pfizer</td><td>243243</td><td></td></tr><tr><td>Open ligating clip appliers Horizon Medium</td><td>Teleflex</td><td>237061</td><td></td></tr><tr><td>PERMAHAND Silk Suture</td><td>PERMA HAND</td><td>SA 63H</td><td></td></tr><tr><td>Pinnacle Introducer sheath</td><td>Terrumo</td><td>RSS102</td><td>sheath length 10cm</td></tr><tr><td>Prolene 3-0</td><td>ETHICON</td><td>8684H</td><td></td></tr><tr><td>Titanium Clips Medium</td><td>Teleflex</td><td>2200</td><td></td></tr><tr><td>Umbilical tape</td><td>Ethicon</td><td>EFA 1165</td><td></td></tr><tr><td>VICRYL 2 coated undyed 1X54&quot; TP-1</td><td>ETHICON</td><td>J 880T</td><td></td></tr><tr><td>Vicryl 2-0</td><td>ETHICON</td><td>J269H</td><td></td></tr></tbody></table>

chronic ovine model of right ventricular failure and functional tricuspid regurgitation

The pathophysiology of severe functional tricuspid regurgitation (FTR) associated with right ventricular dysfunction is poorly understood, leading to suboptimal clinical results. We set out to establish a chronic ovine model of FTR and right heart failure to investigate the mechanisms of FTR. Twenty adult male sheep (6-12 months old, 62 &#177; 7 kg) underwent a left thoracotomy and baseline echocardiography. A pulmonary artery band (PAB) was placed and cinched around the main pulmonary artery (PA) to at least double the systolic pulmonary artery pressure (SPAP), inducing right ventricular (RV) pressure overload and signs of RV dilatation. PAB acutely increased the SPAP from 21 &#177; 2 mmHg to 62 &#177; 2 mmHg. The animals were followed for 8 weeks, symptoms of heart failure were treated with diuretics, and surveillance echocardiography was used to assess for pleural and abdominal fluid collection. Three animals died during the follow-up period due to stroke, hemorrhage, and acute heart failure. After 2 months, a median sternotomy and epicardial echocardiography were performed. Of the surviving 17 animals, 3 developed mild tricuspid regurgitation, 3 developed moderate tricuspid regurgitation, and 11 developed severe tricuspid regurgitation. Eight weeks of pulmonary artery banding resulted in a stable chronic ovine model of right ventricular dysfunction and significant FTR. This large animal platform can be used to further investigate the structural and molecular basis of RV failure and functional tricuspid regurgitation.

Following the completion of the experimental protocol for model development (nearly 8 weeks), the animals were taken back to the operating room for median sternotomy and the implantation of sonomicrometry crystals on the epicardial and intra-cardiac structures. This procedure was performed using cardiopulmonary bypass with the heart beating and with bicaval control, as&#160;described by our group in detail previously9. There were no problems in weaning the animals from the cardiopulmonary bypass o...

Watch this Scientific Journal Video about Chronic Ovine Model of Right Ventricular Failure and Functional Tricuspid Regurgitation at JoVE.com

Chronic Ovine Model of Right Ventricular Failure and Functional Tricuspid Regurgitation

Right ventricular failure and functional tricuspid regurgitation are associated with left-sided heart disease and pulmonary hypertension, which contribute significantly to morbidity and mortality in patients. Establishing a chronic ovine model to study right ventricular failure and functional tricuspid regurgitation will help in understanding their mechanisms, progression, and possible treatments.

The pathophysiology of severe functional tricuspid regurgitation (FTR) associated with right ventricular dysfunction is poorly understood, leading to ...

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607 Views.  Spectrum Health. Het model is vergelijkbaar met de modellen die eerder in de literatuur zijn beschreven. Hoewel ons specifieke doel was om significante functionele tricuspidalisregurgitatie te induceren in plaats van alleen geïsoleerde rechterhartdisfunctie. De techniek kan in de toekomst worden gebruikt om mechanismen van functionele tricuspidalisregurgitatie te bestuderen met de bijbehorende rechterventrikelringvormige en subulaire remodellering, evenals weefselveranderingen.Het model kan nuttig zij...

Video: Chronic Ovine Model of Right Ventricular Failure and Functional Tricuspid Regurgitation

Echocardiographic Assessment of the Right Heart in Mice

Transgenic and toxic models of pulmonary arterial hypertension (PAH) are widely used to study the pathophysiology of PAH and to investigate potential therapies. Given the expense and time involved in creating animal models of disease, it is critical that researchers have tools to accurately assess phenotypic expression of disease. Right ventricular dysfunction is the major manifestation of pulmonary hypertension. Echocardiography is the mainstay of the noninvasive assessment of right ventricular function in rodent models and has the advantage of clear translation to humans in whom the same tool is used. Published echocardiography protocols in murine models of PAH are lacking.
In this article, we describe a protocol for assessing RV and pulmonary vascular function in a mouse model of PAH with a dominant negative BMPRII mutation; however, this protocol is applicable to any diseases affecting the pulmonary vasculature or right heart. We provide a detailed description of animal preparation, image acquisition and hemodynamic calculation of stroke volume, cardiac output and an estimate of pulmonary artery pressure.

This article provides a protocol for the echocardiographic assessment of right ventricular size and pulmonary hypertension in mice. Applications include phenotype determination and serial assessment in transgenic and toxin-induced mouse models of cardiomyopathy and pulmonary vascular disease.

Transgenic and toxic models of pulmonary arterial hypertension (PAH) are widely used to study the pathophysiology of PAH and to investigate potential ...

Assessment of Right Ventricular Structure and Function in Mouse Model of Pulmonary Artery Constriction by Transthoracic Echocardiography

Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure1-3. Moreover, the RV is significantly affected in pulmonary diseases such as pulmonary artery hypertension (PAH). In addition, the RV is remarkably sensitive to cardiac pathologies, including left ventricular (LV) dysfunction, valvular disease or RV infarction4. To understand the role of RV in the pathogenesis of cardiac diseases, a reliable and noninvasive method to access the RV structurally and functionally is essential.
A noninvasive trans-thoracic echocardiography (TTE) based methodology was established and validated for monitoring dynamic changes in RV structure and function in adult mice. To impose RV stress, we employed a surgical model of pulmonary artery constriction (PAC) and measured the RV response over a 7-day period using a high-frequency ultrasound microimaging system. Sham operated mice were used as controls. Images were acquired in lightly anesthetized mice at baseline (before surgery), day 0 (immediately post-surgery), day 3, and day 7 (post-surgery). Data was analyzed offline using software.
Several acoustic windows (B, M, and Color Doppler modes), which can be consistently obtained in mice, allowed for reliable and reproducible measurement of RV structure (including RV wall thickness, end-diastolic&#160;and end-systolic dimensions), and function (fractional area change, fractional shortening, PA peak velocity, and peak pressure gradient) in normal mice and following PAC.
Using this method, the pressure-gradient resulting from PAC was accurately measured in real-time using Color Doppler mode and was comparable to direct pressure measurements performed with a Millar high-fidelity microtip catheter. Taken together, these data demonstrate that RV measurements obtained from various complimentary views using echocardiography are reliable, reproducible and can provide insights regarding RV structure and function. This method will enable a better understanding of the role of RV cardiac dysfunction.

Right ventricle (RV) dysfunction is critical to the pathogenesis of cardiovascular disease, yet limited methodologies are available for its evaluation. Recent advances in ultrasound imaging provide a noninvasive and accurate option for longitudinal RV study. Herein, we detail a step-by-step echocardiographic method using a murine model of RV pressure overload.

Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure1-3. Moreover, ...

Chronic Thromboembolic Pulmonary Hypertension and Assessment of Right Ventricular Function in the Piglet

An original piglet model of Chronic Thromboembolic Pulmonary Hypertension (CTEPH) associated with chronic Right Ventricular (RV) dysfunction is described. Pulmonary Hypertension (PH) was induced in 3-week-old piglets by a progressive obstruction of the pulmonary vascular bed. A ligation of the left Pulmonary Artery (PA) was performed first through a mini-thoracotomy. Second, weekly embolizations of the right lower pulmonary lobe were done under fluoroscopic guidance with n-butyl-2-cyanoacrylate during 5 weeks. Mean Pulmonary Arterial Pressure (mPAP) measured by ritght heart catheterism, increased progressively, as well as Right Atrial pressure and Pulmonary Vascular Resistances (PVR) after 5 weeks compared to sham animals. Right Ventricular (RV) structural and functional remodeling were assessed by transthoracic echocardiography (RV diameters, RV wall thickness, RV systolic function). RV elastance and RV-pulmonary coupling were assessed by Pressure-Volume Loops (PVL) analysis with conductance method. Histologic study of the lung and the right ventricle were also performed. Molecular analyses on RV fresh tissues could be performed through repeated transcutaneous endomyocardial biopsies. Pulmonary microvascular disease in obstructed and unobstructed territories was studied from lung biopsies using molecular analyses and pathology. Furthermore, the reliability and the reproducibility was associated with a range of PH severity in animals. Most aspects of the human CTEPH disease were reproduced in this model, which allows new perspectives for the understanding of the underlying mechanisms (mitochondria, inflammation) and new therapeutic approaches (targeted, cellular or gene therapies) of the overloaded right ventricle but also pulmonary microvascular disease.

Chronic Thromboembolic Pulmonary Hypertension (CTEPH) and Right Ventricular (RV) dysfunction were induced in piglets by progressive obstruction of the pulmonary arteries. Consequences were remarkably similar to those observed in CTEPH patients. This animal model would be a very useful tool for pathophysiology and therapeutic experiments on CTEPH and RV failure.

An original piglet model of Chronic Thromboembolic Pulmonary Hypertension (CTEPH) associated with chronic Right Ventricular (RV) dysfunction is described. ...

A Large Animal Model for Pulmonary Hypertension and Right Ventricular Failure: Left Pulmonary Artery Ligation and Progressive Main Pulmonary Artery Banding in Sheep

Decompensated right ventricular failure (RVF) in pulmonary hypertension (PH) is fatal, with limited medical treatment options. Developing and testing novel therapeutics for PH requires a clinically relevant large animal model of increased pulmonary vascular resistance and RVF. This manuscript discusses the latest development of the previously published ovine PH-RVF model that utilizes left pulmonary artery (PA) ligation and main PA occlusion. This model of PH-RVF is a versatile platform to control not only the disease severity but also the RV&#39;s phenotypic response.
Adult sheep (60-80 kg) underwent left PA (LPA) ligation, placement of main PA cuff, and insertion of RV pressure monitor. PA cuff and RV pressure monitor were connected to subcutaneous ports. Subjects underwent progressive PA banding twice per week for 9 weeks with sequential measures of RV pressure, PA cuff pressures, and mixed venous blood gas (SvO2). At the initiation and endpoint of this model, ventricular function and dimensions were assessed using echocardiography. In a representative group of 12 animal subjects, RV mean and systolic pressure increased from 28 &#177; 5 and 57 &#177; 7 mmHg at week 1, respectively, to 44 &#177; 7 and 93 &#177; 18 mmHg (mean &#177; standard deviation) by week 9. Echocardiography demonstrated characteristic findings of PH-RVF, notably RV dilation, increased wall thickness, and septal bowing. The longitudinal trend of SvO2 and PA cuff pressure demonstrates that the rate of PA banding can be titrated to elicit varying RV phenotypes. A faster PA banding strategy led to a precipitous decline in SvO2 &#60; 65%, indicating RV decompensation, whereas a slower, more paced strategy led to the maintenance of physiologic SvO2 at 70%-80%. One animal that experienced the accelerated strategy developed several liters of pleural effusion and ascites by week 9. This chronic PH-RVF model provides a valuable tool for studying molecular mechanisms, developing diagnostic biomarkers, and enabling therapeutic innovation to manage RV adaptation and maladaptation from PH.

This manuscript describes the surgical technique and experimental approach to develop severe right ventricular pressure overload to model their adaptive and maladaptive phenotypes.

Decompensated right ventricular failure (RVF) in pulmonary hypertension (PH) is fatal, with limited medical treatment options. Developing and testing ...

Bioengineering

Tachycardia-Induced Cardiomyopathy As a Chronic Heart Failure Model in Swine

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment methods. Here, we present such a model by tachycardia-induced cardiomyopathy, which can be produced by rapid cardiac pacing in swine.
A single pacing lead is introduced transvenously into fully anaesthetized healthy swine, to the apex of the right ventricle, and fixated. Its other end is then tunneled dorsally to the paravertebral region. There, it is connected to an in-house modified heart pacemaker unit that is then implanted in a subcutaneous pocket. 
After 4 - 8 weeks of rapid ventricular pacing at rates of 200 - 240 beats/min, physical examination revealed signs of severe heart failure - tachypnea, spontaneous sinus tachycardia, and fatigue. Echocardiography and X-ray showed dilation of all heart chambers, effusions, and severe systolic dysfunction. These findings correspond well to decompensated dilated cardiomyopathy and are also preserved after the cessation of pacing.
This model of tachycardia-induced cardiomyopathy can be used for studying the pathophysiology of progressive chronic heart failure, especially hemodynamic changes caused by new treatment modalities like mechanical circulatory supports. This methodology is easy to perform and the results are robust and reproducible.

Here, we present a protocol to produce tachycardia-induced cardiomyopathy in swine. This model represents a potent way to study the hemodynamics of progressive chronic heart failure and the effects of applied treatment.

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment ...

Invasive Hemodynamic Monitoring of Aortic and Pulmonary Artery Hemodynamics in a Large Animal Model of ARDS

One of the leading causes of morbidity and mortality in patients with heart failure is right ventricular (RV) dysfunction, especially if it is due to pulmonary hypertension. For a better understanding and treatment of this disease, precise hemodynamic monitoring of left and right ventricular parameters is important. For this reason, it is essential to establish experimental pig models of cardiac hemodynamics and measurements for research purpose. 
This article shows the induction of ARDS by using oleic acid (OA) and consequent right ventricular dysfunction, as well as the instrumentation of the pigs and the data acquisition process that is needed to assess hemodynamic parameters. To achieve right ventricular dysfunction, we used oleic acid (OA) to cause ARDS and accompanied this with pulmonary artery hypertension (PAH). With this model of PAH and consecutive right ventricular dysfunction, many hemodynamic parameters can be measured, and right ventricular volume load can be detected. 
All vital parameters, including respiratory rate (RR), heart rate (HR) and body temperature were recorded throughout the whole experiment. Hemodynamic parameters including femoral artery pressure (FAP), aortic pressure (AP), right ventricular pressure (peak systolic, end systolic and end diastolic right ventricular pressure), central venous pressure (CVP), pulmonary artery pressure (PAP) and left arterial pressure (LAP) were measured as well as perfusion parameters including ascending aortic flow (AAF) and pulmonary artery flow (PAF). Hemodynamic measurements were performed using transcardiopulmonary thermodilution to provide cardiac output (CO). Furthermore, the PiCCO2 system (Pulse Contour Cardiac Output System 2) was used to receive parameters such as stroke volume variance (SVV), pulse pressure variance (PPV), as well as extravascular lung water (EVLW) and global end-diastolic volume (GEDV). Our monitoring procedure is suitable for detecting right ventricular dysfunction and monitoring hemodynamic findings before and after volume administration.

We present a protocol of creating right ventricular dysfunction in a pig model by inducing ARDS. We demonstrate invasive monitoring of left and right ventricular cardiac output using flow probes around the aorta and the pulmonary artery, as well as blood pressure measurements in the aorta and pulmonary artery.

One of the leading causes of morbidity and mortality in patients with heart failure is right ventricular (RV) dysfunction, especially if it is due to ...

A Pulmonary Trunk Banding Model of Pressure Overload Induced Right Ventricular Hypertrophy and Failure

Right ventricular (RV) failure induced by sustained pressure overload is a major contributor to morbidity and mortality in several cardiopulmonary disorders. Reliable and reproducible animal models of RV failure are therefore warranted in order to investigate disease mechanisms and effects of potential therapeutic strategies. Banding of the pulmonary trunk is a common method to induce isolated RV hypertrophy but in general, previously described models have not succeeded in creating a stable model of RV hypertrophy and failure.
We present a rat model of pressure overload induced RV hypertrophy caused by pulmonary trunk banding (PTB) that enables different phenotypes of RV hypertrophy with and without RV failure. We use a modified ligating clip applier to compress a titanium clip around the pulmonary trunk to a pre-set inner diameter. We use different clip diameters to induce different stages of disease progression from mild RV hypertrophy to decompensated RV failure.
RV hypertrophy develops consistently in rats subjected to the PTB procedure and depending on the diameter of the applied banding clip, we can accurately reproduce different disease severities ranging from compensated hypertrophy to severe decompensated RV failure with extra-cardiac manifestations.
The presented PTB model is a valid and robust model of pressure overload induced RV hypertrophy and failure that has several advantages to other banding models including high reproducibility and the possibility of inducing severe and decompensated RV failure.

We present a surgical method to induce right ventricular hypertrophy and failure in rats.

Right ventricular (RV) failure induced by sustained pressure overload is a major contributor to morbidity and mortality in several cardiopulmonary ...

Induction and Phenotyping of Acute Right Heart Failure in a Large Animal Model of Chronic Thromboembolic Pulmonary Hypertension

The development of acute right heart failure (ARHF) in the context of chronic pulmonary hypertension (PH) is associated with poor short-term outcomes. The morphological and functional phenotyping of the right ventricle is of particular importance in the context of hemodynamic compromise in patients with ARHF. Here, we describe a method to induce ARHF in a previously described large animal model of chronic PH, and to phenotype, dynamically, right ventricular function using the gold standard method (i.e., pressure-volume PV loops) and with a non-invasive clinically available method (i.e., echocardiography). Chronic PH is first induced in pigs by left pulmonary artery ligation and right lower lobe embolism with biological glue once a week for 5 weeks. After 16 weeks, ARHF is induced by successive volume loading using saline followed by iterative pulmonary embolism until the ratio of the systolic pulmonary pressure over systemic pressure reaches 0.9 or until the systolic systemic pressure decreases below 90 mmHg. Hemodynamics are restored with dobutamine infusion (from 2.5 &#181;g/kg/min to 7.5 &#181;g/kg/min). PV-loops and echocardiography are performed during each condition. Each condition requires around 40 minutes for induction, hemodynamic stabilization and data acquisition. Out of 9 animals, 2 died immediately after pulmonary embolism and 7 completed the protocol, which illustrates the learning curve of the model. The model induced a 3-fold increase in mean pulmonary artery pressure. The PV-loop analysis showed that ventriculo-arterial coupling was preserved after volume loading, decreased after acute pulmonary embolism and was restored with dobutamine. Echocardiographic acquisitions allowed to quantify right ventricular parameters of morphology and function with good quality. We identified right ventricular ischemic lesions in the model. The model can be used to compare different treatments or to validate non-invasive parameters of right ventricular morphology and function in the context of ARHF.

We present a protocol to induce and phenotype an acute right heart failure in a large animal model with chronic pulmonary hypertension. This model can be used to test therapeutic interventions, to develop right heart metrics&#160;or to improve the understanding of acute right heart failure pathophysiology.

The development of acute right heart failure (ARHF) in the context of chronic pulmonary hypertension (PH) is associated with poor short-term outcomes. The ...

A Novel Right Ventricular Volume and Pressure Loaded Piglet Heart Model for the Study of Tricuspid Valve Function.

Heart conditions in which the tricuspid valve (TV) faces either increased volume or pressure stressors are associated with premature valve failure. Mechanistic studies to improve our&#160;understanding of the underlying pathophysiology responsible for the development of premature TV failure are lacking. Due to the inability to conduct these studies in humans, an animal model is required. In this manuscript, we describe the protocols for a novel chronic recovery infant piglet heart model for the study of changes in the TV when placed under combined volume and pressure stress. In this model, volume loading of the right ventricle&#160;and the TV is achieved through the disruption of the pulmonary valve. Then pressure loading is accomplished through the placement of a pulmonary artery band. The success of this model is assessed at four weeks post intervention surgery through echocardiography, intracardiac pressure measurement, and pathologic examination of the heart specimens.

A novel recovery piglet heart model with combined pressure and volume overload on the right ventricle is described for the study of tricuspid valve function.

Heart conditions in which the tricuspid valve (TV) faces either increased volume or pressure stressors are associated with premature valve failure. ...

Creating a Murine Model of RV Hypertrophy and Failure by Pulmonary Trunk Banding

A Murine Model of Pressure Overload-Induced Right Ventricular Hypertrophy and Failure by Pulmonary Trunk Banding

Right ventricular (RV) failure caused by pressure overload is strongly associated with morbidity and mortality in a number of cardiovascular and pulmonary diseases. The pathogenesis of RV failure is complex and remains inadequately understood. To identify new therapeutic strategies for the treatment of RV failure, robust and reproducible animal models are essential. Models of pulmonary trunk banding (PTB) have gained popularity, as RV function can be assessed independently of changes in the pulmonary vasculature.
In this paper, we present a murine model of RV pressure overload induced by PTB in 5-week-old mice. The model can be used to induce different degrees of RV pathology, ranging from mild RV hypertrophy to decompensated RV failure. Detailed protocols for intubation, PTB surgery, and phenotyping by echocardiography are included in the paper. Furthermore, instructions for customizing instruments for intubation and PTB surgery are given, enabling fast and inexpensive reproduction of the PTB model.
Titanium ligating clips were used to constrict the pulmonary trunk, ensuring a highly reproducible and operator-independent degree of pulmonary trunk constriction. The severity of PTB was graded by using different inner ligating clip diameters (mild: 450 &#181;m and severe: 250 &#181;m). This resulted in RV pathology ranging from hypertrophy with preserved RV function to decompensated RV failure with reduced cardiac output and extracardiac manifestations. RV function was assessed by echocardiography at 1 week and 3 weeks after surgery. Examples of echocardiographic images and results are presented here. Furthermore, results from right heart catheterization and histological analyses of cardiac tissue are shown.

Author Spotlight: Investigating the Underlying Mechanisms of Right Ventricular Failure in Pulmonary Hypertension

We describe a murine model of right ventricular pressure overload-induced by pulmonary trunk banding. Detailed protocols for intubation, surgery, and phenotyping by echocardiography are included in the paper. Custom-made instruments are used for intubation and surgery, allowing for fast and inexpensive reproduction of the model.

Right ventricular (RV) failure caused by pressure overload is strongly associated with morbidity and mortality in a number of cardiovascular and pulmonary ...

Chronic Ovine Model of Right Ventricular Failure and Functional Tricuspid Regurgitation

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